BackgroundPostpartum Depression (PPD) is a severe mental health condition that adversely affects mothers and their infants. The influence of PPD on maternal-infant bonding and breastfeeding practices has been scarcely reported in Nigeria. Therefore, we examined the prevalence of PPD, the associated factors, and the relationship with maternal-infant bonding and breastfeeding practices in Abeokuta, Nigeria.MethodA descriptive cross-sectional survey was conducted among 600 mothers within the extended postpartum period (≤ 1 year) from three government-owned immunisation clinics at primary, secondary, and tertiary health facilities in Abeokuta, Ogun State. PPD was assessed using the Edinburgh postnatal depression Scale (EPDS ≥ 13), and maternal-infant bonding was evaluated using the Postpartum Bonding Questionnaire (PBQ ≥ 50). We also examined breastfeeding practices (i.e. the time to initiation by 30 min, exclusive breastfeeding for 6 months and early commencement of complementary feeding by 2 months). Data was analysed using chi-square and logistics regression models at a 5% significance level.ResultsThe prevalence of PPD was 21.8%, 95% CI (18.7–25.3). Factors associated with PPD were maternal age: 25–34 years [AOR = 0.52; 95% CI (0.29–0.90)]; ≥ 35 years [AOR = 0.44; 95% CI (0.20–0.96)], being married [AOR = 0.43; 95% CI (0.21–0.85)], perceived stress increased the odds of PPD: moderate stress level [AOR = 8.38; 95% CI (3.50–19.9)]; high-stress level [AOR = 47.8; 95% CI (8.65–263.7)] and self-reported history of emotional problems [AOR = 3.25; 95% CI (1.43–7.38)]. There was a significant direct association between PPD and poor maternal-infant bonding [AOR = 3.91; 95% CI (1.04–4.60)]. PPD reduces the odds of early breastfeeding initiation [AOR = 0.43; 95% CI (0.28–0.68)], but no association was found between PPD and exclusive breastfeeding [AOR = 1.07; 95% CI (0.07–1.67)].ConclusionThe prevalence of PPD was high in our study population and associated with poor maternal-infant bonding and late breastfeeding initiation but not with exclusive breastfeeding. Promoting maternal mental health to foster stronger mother-infant relationships and better breastfeeding practices has become crucial.